A continuously variable transmission comprises a first pulley assembly connected to an internal combustion engine, a second pulley assembly connected to the vehicle wheels and a belt wound between the two pulley assemblies.
Each assembly generally comprises a shaft connected to the engine or to the wheels, a supporting element driven by the shaft, and a pair of half pulleys rigidly and rotationally connected to the supporting element and reciprocally mobile along the rotatable supporting element to define the transmission ratio.
According to the various transmission configurations, one of the two pulley assemblies also comprises a clutch for selectively coupling the shaft to the supporting element for driving the half pulleys.
Continuously variable transmissions are applied to scooters and, thanks to the increased transmissible power, also to other vehicles, such as three- or four-wheel vehicles or snowmobiles.
However, the driving modes of a four-wheel vehicle are different from those of a scooter and in particular a need to fully exploit exhaust brake is felt.